Re: [PATCH] tracing/filters: Defer pred allocation

Frederic Weisbecker
2009-08-31T17:41:11Z

On Mon, Aug 31, 2009 at 04:49:41PM +0800, Li Zefan wrote:
> @@ -1094,6 +1118,10 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string)
>
> mutex_lock(&event_mutex);
>
> + err = init_preds(call);
> + if (err)
> + goto out_unlock;

Hmm, but what happens if the filter already has its preds initialized
by a previous filter?

The first thing that init_preds() does is:

filter = call->filter = kzalloc(sizeof(*filter), GFP_KERNEL);

That looks like a memory leak.

> if (!strcmp(strstrip(filter_string), "0")) {
> filter_disable_preds(call);
> remove_filter_string(call->filter);
> @@ -1139,6 +1167,10 @@ int apply_subsystem_event_filter(struct event_subsystem *system,
>
> mutex_lock(&event_mutex);
>
> + err = init_subsystem_preds(system);

Whereas this one has a check:
if (!call->filter)
alloc...

> + if (err)
> + goto out_unlock;
> +
> if (!strcmp(strstrip(filter_string), "0")) {
> filter_free_subsystem_preds(system, FILTER_DISABLE_ALL);
> remove_filter_string(system->filter);
> diff --git a/kernel/trace/trace_export.c b/kernel/trace/trace_export.c
> index 029a91f..df1bf6e 100644
> --- a/kernel/trace/trace_export.c
> +++ b/kernel/trace/trace_export.c
> @@ -135,7 +135,6 @@ __attribute__((section("_ftrace_events"))) event_##call = { \
> static int ftrace_raw_init_event_##call(void) \
> { \
> INIT_LIST_HEAD(&event_##call.fields); \
> - init_preds(&event_##call); \
> return 0; \
> } \
>
> --
> 1.6.3
>

Other than the above doubts, that looks good.